The Vanishing Melodies of the Thrush Nightingale: A Songbook Rewritten
Researchers in Poland studying Thrush Nightingales have made the remarkable discovery that not single song type from 1986 was still in use in 2019.
For centuries, birdwatchers and naturalists alike have marvelled at the musical complexity of the Thrush Nightingale. Known for its rich and intricate repertoire, this enigmatic songbird has long been a subject of fascination. Now, a recent study published in Avian Research has revealed an astonishing development: the songs of this species have undergone a complete transformation over just three decades.
A Lost Repertoire
A team of researchers led by Abel Souriau from Charles University in Prague compared recordings of Thrush Nightingales from 1986 and 2019 in the same locality in south-eastern Finland. Their findings were nothing short of remarkable. Not a single song type from 1986 was still in use in 2019, indicating a full-scale turnover of song patterns within the species. While 40% of the syllables (the building blocks of bird songs) remained the same, the structured sequences forming distinct song types had vanished and been replaced by new ones.
The Science Behind the Change
Birdsong plays a crucial role in species recognition, mate attraction, and territorial defence. Many species develop dialects - local variations of song - passed down through generations. While previous studies have focused on birds with simpler songs, the Thrush Nightingale presents an intricate case.
The researchers noted that while song type repertoires shrank over time, individual songs became longer. Moreover, birds in 1986 shared more song types with each other compared to their modern-day counterparts. Such divergence suggests that factors like cultural drift, environmental changes, or even shifts in population density may have played a role in reshaping the birds’ songs.
A Case of Rapid Cultural Evolution?
Unlike genetic evolution, which takes place over many generations, cultural evolution - particularly in learned behaviours like birdsong - can occur much more rapidly. Some studies have shown that birds can adapt their songs in response to environmental changes, such as urban noise pollution, but in the case of the Thrush Nightingale, the changes appear more deeply ingrained in social learning patterns.
Interestingly, this level of change is not observed in its close relative, the Common Nightingale (Luscinia megarhynchos). Previous research has found that Common Nightingales retain a stable core of song types even over nearly seven decades. The contrast between these two species raises questions about what drives such stark differences in song stability.
What Comes Next?
This discovery highlights the need for more long-term studies into song evolution in complex-singing birds. While the study provides compelling evidence of rapid song change, it remains unclear whether these changes were gradual or occurred in abrupt shifts. Could new generations of Thrush Nightingales simply favour innovation over tradition? Or did external pressures - such as shifting migration patterns or changes in habitat - accelerate this vocal transformation?
One thing is certain: the forests and wetlands of Finland now echo with an entirely new melody, a chorus distinct from the one that filled the air three decades ago. For bird enthusiasts, the Thrush Nightingale remains a symbol of nature’s ever-changing songbook - a mystery still waiting to be fully deciphered.
Read the full paper here.
4 Mar 2025
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